“After the terrorist attacks of Sept. 11, 2001, for instance, time horizons for many people in the United States shortened. People, especially those in big cities like New York, increasingly adopted a ‘live for the day’ attitude. Activities with long-term benefits, like diet and exercise, were out; treating oneself well in the here and now was in. One result: the diet chain Jenny Craig reported ‘a huge wave of cancellations.’”